Mechanochromic systems for the detection of stress, strain and deformation in polymeric materials

The detection of stress in polymeric materials such as plastics, elastomers, composites and coatings is critical in the monitoring of material failure including stress fractures, fatigue and hysteresis. Mechanochromic systems that utilise a change in fluorescent output as a result of the mechanical deformation of a polymer have only been actively investigated relatively recently and whilst the field is still relatively small a considerable number of examples of such systems now exist. This article will discuss the principles behind such systems and review examples in the literature and survey the most common fluorophores used in such systems including phenylene vinylene oligomeric derivatives, polycyclic aromatic compounds, carbazole derivatives and conjugated polymers.